The objective of the proposed program is to determine quantitatively the effect of stress upon bone remodeling. Analysis by finite elements of specific mechanical stress fields of the rabbit calvarium is proposed. Bone remodeling in these mechanical stress situations will be measured by injecting dyes, such as tetracycline, which fluoresce in ultraviolet light. A mathematical model which is presently established will be modified to represent the quantitative relationship between the stress field and the osteosynthesic activity in the bone. An attempt will be made to clarify the relationship between compressive stresses and remodeling which are presently in doubt. The first experiment will involve a constant load device to impose constant compressive stresses during the period of remodeling. Stress-remodeling history of the experiment will be obtained by labeling the bone with the dyes sequentially. A second experiment will involve the same protocol except that the stresses will be allowed to decrease in a manner similar to those found when compression devices are normally applied. As before, a stress-time history of remodeling will be obtained. Bone from geographical locations within the stress field will be compared to predicted stresses from the model for that same region.